Comment 1 for bug 75695

Was going to log a new bug, but this one looks very similar. Heres the details I found.

Peter try setting LANG to something matching under /usr/lib/locale and run your test to see if we have the same bug. probably en_CA.utf8

----------------------------------------------------------------------------

Ive noticed a small performance hit arising from locale settings. Ubunutu (gnome-language-selector) sets lang in a format like:

LANG=en_AU.UTF-8
LANGUAGE=en_AU:en
LC_CTYPE="en_AU.UTF-8"
LC_NUMERIC="en_AU.UTF-8"
LC_TIME="en_AU.UTF-8"
LC_COLLATE="en_AU.UTF-8"
LC_MONETARY="en_AU.UTF-8"
LC_MESSAGES="en_AU.UTF-8"
LC_PAPER="en_AU.UTF-8"
LC_NAME="en_AU.UTF-8"
LC_ADDRESS="en_AU.UTF-8"
LC_TELEPHONE="en_AU.UTF-8"
LC_MEASUREMENT="en_AU.UTF-8"
LC_IDENTIFICATION="en_AU.UTF-8"

When binaries are executed, the LANG is looked up in /usr/lib/locale, which on my system looks like:

xxx@xxx:/usr/lib/locale$ ls
en_AU.utf8 en_DK.utf8 en_IE.utf8 en_PH.utf8 en_ZA.utf8
en_BW.utf8 en_GB.utf8 en_IN en_SG.utf8 en_ZW.utf8
en_CA.utf8 en_HK.utf8 en_NZ.utf8 en_US.utf8

They dont match up, en_AU.utf8 vs en_AU.UTF-8

With the default LANG, running strace across various binaries, 'ls' for example gives many messages such as:
open("/usr/lib/locale/en_AU.UTF-8/LC_CTYPE", O_RDONLY) = -1 ENOENT (No such file or directory)

With LANG=en_AU.UTF-8
strace -c ls
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
100.00 0.000062 4 14 read
  0.00 0.000000 0 1 write
  0.00 0.000000 0 105 77 open
  0.00 0.000000 0 29 close
  0.00 0.000000 0 1 execve
  0.00 0.000000 0 12 12 access
  0.00 0.000000 0 3 brk
  0.00 0.000000 0 2 2 ioctl
  0.00 0.000000 0 6 munmap
  0.00 0.000000 0 1 mprotect
  0.00 0.000000 0 1 _sysctl
  0.00 0.000000 0 2 rt_sigaction
  0.00 0.000000 0 1 rt_sigprocmask
  0.00 0.000000 0 1 getrlimit
  0.00 0.000000 0 42 mmap2
  0.00 0.000000 0 29 fstat64
  0.00 0.000000 0 2 getdents64
  0.00 0.000000 0 1 fcntl64
  0.00 0.000000 0 2 futex
  0.00 0.000000 0 1 set_thread_area
  0.00 0.000000 0 1 set_tid_address
------ ----------- ----------- --------- --------- ----------------
100.00 0.000062 257 91 total

With LANG=en_AU.utf8, to match the directory in /usr/lib/locale
strace -c ls
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
   nan 0.000000 0 14 read
   nan 0.000000 0 3 write
   nan 0.000000 0 93 65 open
   nan 0.000000 0 29 close
   nan 0.000000 0 1 execve
   nan 0.000000 0 12 12 access
   nan 0.000000 0 3 brk
   nan 0.000000 0 2 ioctl
   nan 0.000000 0 6 munmap
   nan 0.000000 0 1 mprotect
   nan 0.000000 0 1 _sysctl
   nan 0.000000 0 2 rt_sigaction
   nan 0.000000 0 1 rt_sigprocmask
   nan 0.000000 0 1 getrlimit
   nan 0.000000 0 42 mmap2
   nan 0.000000 0 29 fstat64
   nan 0.000000 0 2 getdents64
   nan 0.000000 0 1 fcntl64
   nan 0.000000 0 2 futex
   nan 0.000000 0 1 set_thread_area
   nan 0.000000 0 1 set_tid_address
------ ----------- ----------- --------- --------- ----------------
100.00 0.000000 247 77 total

Having a LANG that doesn't match a directory in /usr/lib/locale generates 10 more system calls, and 14 more errors.

Testing something a bit more substantial than 'ls', heres the summary of the first process for firefox.

export LANG=en_AU.UTF-8
strace -c firefox
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
100.00 0.000684 7627 2064 total

export LANG=en_AU.utf8
strace -c firefox
% time seconds usecs/call calls errors syscall
------ ----------- ----------- --------- --------- ----------------
100.00 0.000446 7550 2039 total

77 More system calls.

Reporting this because every little bit of performance helps.

Andrew Hendry.